Goodwill and Other Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets
Gross Carrying Value	$ 87,678	$ 88,181
Accumulated Amortization	(35,877)	(30,741)
Net Carrying Amount	51,801	57,440
Non-compete agreements
Finite-Lived Intangible Assets
Gross Carrying Value	4,215	4,238
Accumulated Amortization	(3,757)	(3,100)
Net Carrying Amount	458	1,138
Patents
Finite-Lived Intangible Assets
Gross Carrying Value	379	389
Accumulated Amortization	(172)	(164)
Net Carrying Amount	207	225
Customer relationships
Finite-Lived Intangible Assets
Gross Carrying Value	37,333	37,679
Accumulated Amortization	(10,869)	(9,171)
Net Carrying Amount	26,464	28,508
Trademarks and trade names
Finite-Lived Intangible Assets
Gross Carrying Value	10,057	10,085
Accumulated Amortization	(4,710)	(4,091)
Net Carrying Amount	5,347	5,994
Technology
Finite-Lived Intangible Assets
Gross Carrying Value	35,694	35,790
Accumulated Amortization	(16,369)	(14,215)
Net Carrying Amount	$ 19,325	$ 21,575
Weighted Average
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	15 years
Weighted Average | Non-compete agreements
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	5 years	5 years
Weighted Average | Patents
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	10 years	10 years
Weighted Average | Customer relationships
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	18 years	17 years
Weighted Average | Trademarks and trade names
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	14 years	14 years
Weighted Average | Technology
Finite-Lived Intangible Assets
Weighted Average Amortization Period In Years	14 years	14 years